5. what is the midpoint of the segment joining (12,2) and (-5,-7)? a.(5,-3) b.(9,17) c.(8.5,4.5) d.(3.5,-2.5) 6.the diameter of a circle has endpoints (-2,0) and (2,1).which is closest to the length of the diameter of the circle? a.4 b.1 c.5 d. square root of 17 7.the distance between the points (-2,-4) and (3,8) is: a. square root of 17 b.13 c.169 d.17

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.